package com.example.base;

public class LinkListTest2 {

    //测试类
        public static void main(String[] args) throws Exception {
            Node<String> first = new Node<String>("aa", null);
            Node<String> second = new Node<String>("bb", null);
            Node<String> third = new Node<String>("cc", null);
            Node<String> fourth = new Node<String>("dd", null);
            Node<String> fifth = new Node<String>("ee", null);
            Node<String> six = new Node<String>("ff", null);
            Node<String> seven = new Node<String>("gg", null);
//完成结点之间的指向
            first.next = second;
            second.next = third;
            third.next = fourth;
            fourth.next = fifth;
            fifth.next = six;
            six.next = seven;
//产生环
            seven.next = third;
//判断链表是否有环
            boolean circle = isCircle(first);
            System.out.println("first链表中是否有环："+circle);
        }
        /**
         * 判断链表中是否有环
         * @param first 链表首结点
         * @return ture为有环，false为无环
         */
        public static boolean isCircle(Node<String> first) {
            Node<String> slow = first;
            Node<String> fast = first;
            while(fast!=null && fast.next!=null){
                fast = fast.next.next;
                slow = slow.next;
                if (fast.equals(slow)){
                    return true;
                }
            }
            return false;
        }
        //结点类
        private static class Node<T> {
            //存储数据
            T item;
            //下一个结点
            Node next;
            public Node(T item, Node next) {
                this.item = item;
                this.next = next;
            }
        }


}
